Catheters are tube-like members inserted into the body for diagnostic or therapeutic reasons. One of the therapeutic procedures applicable to the present invention is known as percutaneous transluminal coronary angioplasty (PTCA). This procedure can be used, for example, to reduce arterial build-up of cholesterol fats or atherosclerotic plaque. Using a movable wire system, one could more readily select the desired coronary artery and reach smaller branches as movable guidewires are smaller and more flexible than the fixed wire systems. The catheter is subsequently tracked over the guidewire to the stenosis. The balloon at the distal end of the catheter is then inflated causing the site of the stenosis to widen. After the balloon is deflated, the catheter is withdrawn over the guidewire and another catheter can be slid into place over it if necessary.
Various versions of rapid exchange catheters, either coaxial or biaxial, are shown in the following patents: U.S. Pat. Nos. 4,762,129 and 5,232,445 issued to Bonzel, U.S. Pat. Nos. 5,040,548 and 5,061,273 issued to Yock, U.S. Pat. No. 4,748,982 issued to Horzewski, et at., U.S. Pat. No. 4,988,356 issued to Crittenden, U.S. Pat. No. 5,135,535 issued to Kramer; U.S. Pat .No. 5,180,367 to Kontos; assignee's WO 94/11048 issued to Jung et at.; assignee's WO 94/11053 issued to Ndondo-Lay et at.; and assignee's copending application 08/149,887 to Khairkhahan et at.
The following are examples of spring coil catheters. Some catheters, such as the present assignee's 14K.TM. catheter and Thruflex.RTM. catheter to Solar and Roucher (shown in U.S. Pat. No. 4,917,666) are over-the-wire catheters having spring coil lumens to improve the pushability of the catheter. At the same time, the spring coil is flexible laterally, with minimized kinking. In the present assignee's Gold X.TM. catheter, a coaxial rapid exchange catheter shown in U.S. Pat. No. 5,328,472 issued Jul. 12, 1994 to Steinke et al., the outer lumen is similarly made of a spring coil, with a core wire extending through a portion of the coil for added pushability. In the present assignee's Omniflex.TM. catheter to Buchbinder and Solar (shown generally in U.S. Pat. No. 4,723,936) as sold, a proximal hypotube about 3.81 cm (1.50 inches) long improves the handling of the catheter, which is otherwise formed of a spring coil.
The following illustrates distal balloon bonds used in the prior art. Adhesives are used in U.S. Pat. No. 4,748,982 to Horzewski et al. (col. 3, lines 18-27); in U.S. Pat. No. 4,782,834 to Maguire et al. (col. 3, lines 50-53); in U.S. Pat. No. 5,154,725 to Leopold (cyanoacrylate such as Loctite.TM. 404, col. 5, lines 6-8); in U.S. Pat. No. 5,156,594 to Keith (Epoxy or cyanoacrylate, col. 8 lines 21-24); in U.S. Pat. No. 5,156,595 to Adams (Epoxy, col. 3, lines 37-41); and in U.S. Pat. No. 5,290,230 to Ainsworth et al. (col. 6, lines 27-30).
Heat shrinking is used in U.S. Pat. No. 4,748,982 to Horzewski et al. (col. 3, lines 22-27). Necking down is used in U.S. Pat. No. 4,790,315 to Mueller et al. (col. 4, claim 7). Bonding is used in U.S. Pat. No. 5,061,273 to Yock (col. 2, lines 55-58). A bonded twisted section is used in U.S. Pat. No. 5,108,525 to Gharibadeh (col. 4, lines 12-19).
What is needed is a method of attaching the distal end of a balloon which is reliable and minimizes the distal bond profile.